Can it be possidable to make the Esper Terra into Cosmos from Dissidia?

I don't know if you are talking about FF6 spriting or making a FFD sprite. If you are talking about FFD sprite I can't help you there. If you are talking about a FF6 sprite then here goes:

1.) Impossible? HECK NO!
2.) How to do this:
i) Export Esper Terra and Import her onto desired character.
ii)Change Palette (making sure you have 11 colors in which will be all the colors used for character
iii) Edit said character
iv) Save said character
v) Voila! There you go, you now have Cosmos from Dissidia in FF6 as a playable character!

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Here is an example of a Cosmos I did using Esper Terra as my base:



now that I think about it, I didn't put in her crown her her wrap, I'll put those in and update it.

Here's her with her wrap (crown is impossible to put in there, sry)